On the day mini-amps were invented ... [Frank Olson Music] took apart an old pair of headphones and salvaged the speakers — perhaps intending to replicate a vintage sound — and set them ...

Then in the other half of the shell went the 4Ω 2 W mini speaker. [Penguin DIY] of course drilled a ton of little holes in the shell for the sound to come through. Also on this side are three ...